Air or gas pump, &amp;c.



PATENTED APR. 9, 1907.

G. MAOHLET, JR; AIR OR GAS PUMP, 8w.

APPLICATION FILED NOV. 23, 1904.

3 SHEETS-SHEET 1.

eAsMAm INVENTOR Z BY ATTORIV No. 849.482. PATENTED APR. 9, 1-907.

. G. MAGHLET, J3.

AIR 0R GAS PUMP, 8w. APPLIOATIOVN rum) nov. 23. 1904.

a mama-sum a.

GEORGE MACIILET, TR, OF ELIZABETH, NEW JERSEY.

AIR on GAS PUMP, &.e.

Specification of Letters Patent.

Patented April 9, 1907.

Application filed November 23, 1904. Serial No. 234,026.

2"0 all whom, it may concern:

.' Elizabeth, in thecounty of Union and State of New Jersey, have. invented certain new and useful Improvements -in Air or Gas Pumps, &c., of which the following is a speciiieation.

This invention relates, primarily, to means for enabling a gas-main to deliver more than its normal Volume of gas. in some instancesas, for instance, in using gas-furnaecs for annealing, hardening, brazing, forging, &c.-the gas must be delivered to the furnaces in larger quantities than the gaslnains are usually capable of supplying. It is often the practice to mix air with the gas supplied to the burners, and by compression of the'air and the employment of suitable apparatus to mix the air with the gas a suilicient quantity of the latter can be forced into the furnacesthat is, compressed air has been utilized to draw gas in abnormal quantities from the gas-main and introduce it into the furnaces. It often happens, however, that the gas is of such low grade that it would be a detriment to mix any air with it, and hence it becomes impracticable to utilize com ressed air for introducing the gas into the urnaces.

It will be understood that in order to em ploy a gas-furnace economically it must have a contracted heating-space in proportion to the article to be heated and in order to ob fore, isto provide practicable means for supplying gas in the required volume or at the required pressure in excess of the normal volume or pressure of the gas-main.

Gas is also quite extensively used at the present day in Bunsen burners for heating, cooking, and other domestic purposes and in both small and large manufacturing establishments, and owing to the rapidly-growing demand for gas for these purposes it often happens that the gas-mains that are already laid in the streets of a city are found to be Wholly inadequate, with the result that the gas is supplied under insullicient pressure to the many consumers. My invention has for one of its objects the enabling of gas-mains to meet such unforeseen demands and supply the required volume of gas at normal pressure.

In carrying out my invention 1 employ a pump, which may be driven by a belt, an electric motor, or other means, by which the gas is drawn from the main and supplied to the burners under increased pressure and in greater volume than could be supplied by iilu main ii imaided. The problem of keeping the pump in constant operation without on the one hand causing great fluctuations in the pressure at the burners, owing to the va riable rate of consumption of the gas due to turning on andofl' burners from time'to time, and without on the other hand incurring waste of surplus gas delivered by the pump 1 have solved by means presently .to be described.

The invention also includes means for increasing or diminishing at will the pressure of the gas delivered by the pump, which will be found useful in many situations.

In the accompanying drawings, Figure 1 is a diagrammatic sectional elevation of a pump connected to a gas-main and also connected by a service-pipe to burners of gasfurnaecs, and Fig. 2 is a plan of the pump,

- Fig. 1 being taken at about the line E F of Fig. 2. Fig. 3 illustrates the use of the pump for pumping gas and mixing air therewith, the valve being shown in section which con trols the mixture. Fig. 4 is a sectional view on the line A B of Fig. 3. Fig. 5 is a sectional view on the line C Dof Fig. 3.

A portion of the gas-main or of a pipe leading thereto is seen at 1, and a short vertical pipe 2 leads therefrom to an admission or suetion chamber or port 3 in a pump 4. Any so t of ump, whether rotary or reciprocat ing or in the nature of either a blower or a compressor, may be used for the purpose of my invention, that chosen for illustration being of a rotary piston-pu1np of a type suitable for producing pressures up to a few pounds per square inch, beyond which it is seldom desired to increase the pressure of gas for consumption. Gas is being drawn through the chamber 3 by piston 5, which is one of aset of four equidistant pistons revolving in a cylinder 6 and carried around by four symmetrically-disposed arms 7, projecting from a hub 8, fixed upon a shaft 9, provided with fast and loose pulleys 1011. In this type of pump the shaft 5) is eccentric to the der,-the'-grooves being concentric with cylinder 6. The pistons slide radially in grooves 13, formed in the arms 7. The space between piston 5 and the piston H m advance thereof is lilled with gas that has just been drawn from the main. At the same time the gas in advance of piston 14 is being discharged into or through a delivery chamber or port 15. The remaining pistons 16 and 17, shown at the lower portion of the pump, are temporarily idle, and to prevent escape of gas from'chamber 15 to chamber 3 a saddle or partition 18. is provided at the bottom of the pump, in constant contact with which runs a drum 19, which contains and is formed integral with the arms 7, within which the pistons retire when swinging around in the bottom .of the pump.

Upon the delivery side of the mum is erected a vertical pipe structure, the lower part of which is designated as 20 and the upper part as 21. From the part 20 is led a service or delivery piping 22 with branches at I 23 24 to the burners, some of which are seen at 25, projecting within gas-furnaces 26, each burner being usually provided with a valve 27 for opening and closing the same. It will be understood, however, that the invention is adapted for all kindsof burners used for all sorts of purposes.

It will be perceived that the apparatus so far described is capable of drawing an abnormal supply of gas from the main and delivering it to the burners under pressure greatly above that of the normal pressure in the main. So long as the quantity consumed by the burners kept pace with the capacity of ;the pump nothing more would 'be needed;

but owing to the necessity of regulating the burners and at one run time using a few burners and at another time using many the quantity of gas consumed in practice varies greatly, while for most purposes it is important that the pressure in the service-pipe 22 or at the burners should be uniform wholly regardless of the quantity of gas being con- I sumed. The pump of course should be of a capacity to supply the maximum quantity under the maximum pressure needed at the burners, and since it would be desirable to keep the pump in constant operation during the time that one or more burners are being used provision is made for disposing of the surplus gas delivered by the pump. This surplus escapes through a pipe or passage 28, which leads from the pipe structure 20 on the delivery side'of the pump to the pipe 2 on the admission or intake side'thereof. Through this pipe 28, therefore, the delivery and ad mlsslon sides of the pump are in communication, and it will also be understood that not 'loss of gas.

only the admission side but also the delivery. side. of the pump is in communication with the gas-main. in using the terms admission side and delivery side reference is bad to the operation of the pump, and it is not intended that the physical structure of, the pump is necessarily such that the suction and delivery ports or chambers are upon opposite sides of the pump, since in some pumps they are upon the same-side or upon the top or bottom or one within the other, and any of these pumps may be used for the purpose of my invention, provision being made for communication between the delivery and suct on ports, since the operation of the pump is such that the excess gas delivered is immediately drawn in at the suction-port, the pumphence running idly so far as this excess of gas is concerned.

At any suitable point in the passage between the delivery and suction sides or ports of the pump is placed a relief-valve, which opens whenever the pressure upon the -deliv ery side is in excess and permits the excess gas to escape, thus making it practicable to deliver the gas to the service-pipe at substantially uniform pressure regardless of the quantity being used atthe burners; the escaping gas of course returning to the suction side or port of the pump, so that there is no The valve may be of any suitable kind and operated in any suitablemanner and placedat any desired point between the intake and delivery of the pump. I prefer, however, to form a cylindrical valve 29 upon the bottom end of a rod 30,'which fits within the upper portion 21 of the vertical pipe structure, this portion forming a casing or cylinder within which the rod may move up and down.

Between the parts 20 and 21 is formed a chamber 31, into which each of said ,parts projects, the top of the lower part forminga seat 32 for said valve, whereby the passage between the delivery and admission of the pump is normallyclosed. The casing 21 is surmounted by ahead 33, in which is mount-- ed a diaphragm or flexible disk 34, usually made'of soft rubber. To this diaphragm the rod 30 is connected by means of upper and lower disks 35 36, between which the central portion of the diaphragm is securely held, the rod extending up through the head and carrying removable weights 37 and the disk 35 having a hub or boss 38, whereby it is secured to the rod. By. themovements of the diaphragm the valve 29 is opened and closed,

g 42, formed in the sides of the upper bearing portion of the rod above said recess and communicating therewith, said passages 42 opening into the head 33; .It will be seen that while the gas pressing up against the valve itself may tend to raise the same still owing to the low pressureat which the gas is delivered this lifting power would be so slight as to be ineffectual, while the diaphragm 34 presents a great area to the pressure of the gas, and hence is enabled to control the valve, which, it will be noted, opens an orifice which is small or undersized in proportion to the area of the diaphragm. The pipe 28 is shown attached directly to the chambered portion 31 of the structure.

By means of the weights 37 or any other suitable device the pressure may be regulated of the gas delivered by the pump to the burners, since by the addition of a weight the resistance offered by the diaphragm to the gas pressure is increased, and hence agreater pressure of gas must be produced by the pump in order to lift the diaphragm and the valve, while if weights are removed from the rod the valve is more easily lifted and the gas hence more readily escapes into the pas sage 28, so that the pressure of the delivered gas cannot rise so high.

In case the burners or the discharge portion of the service-pipe is removed from the pump a pipe 43 may be led from such discharge portion back to the head 33, containing the diaphragm, so that the movements of the valve shall be determined by the pressure of the gas in this remote portion of the system, where it is weaker than at the pump itself, owing principally to the friction of the gas flowing through the delivery piping. The passage for gas through the valve-rod may be closed by a central rod 44, having at its upper end a handle 45 and at its lower end a cone 46, adapted to fit a seat in the upper end of passage 39 in the valve. This passage may therefore be closed when returnpipe 43 is in use. The latter may also be provided with a valve 47, so that it may be closed whenever it is desired to admit gas directly to the head 33 through the valverod 30.

It will be perceived that by this invention gas. may be forced into gas-furnaces and other apparatus at a pressure much above that normal to the gas-main and also in numerous cases where the demand for gas at normal gas-main pressure has outgrown the capacity of the main the pump, with its appurtenances, may be introduced for the purpose of Sn plying normal pressure service 1n a hotel, actory, or other building inadequat elysupplied by the unaided main. In some cases the appliance may be connected between two portions of the gas-main itself that is, the parts 1 and 22 may be regarded as adjoining sections of a single gasmain and it will be seen that by this means the efficiency of the main upon the delivery side of the pump will be increased, so that the invention has special advantages where several towns'or manufacturing plants are supplied from a single gas plant and elsewhere in cases involving the flow of gas for a reat dist ance from its origin to the point where it is used, and the necessity of laying gas-mains of undue size or of taking up old mains and replacing them wit-h mains of larger size or of laying supplemental mains is avoided. Again, where a gas-main has been laid for supplying a rich quality of gas and it becomes desirable to use the main for a low-grade gas the main is found to be too small to supply the low-grade gas in such increased volume as to compensate for its deficiency in quality; but this difficulty is overcome by my invention, which makes it practicable to supply the gas to consumers at any desired pressure, the uniformity of which is preserved without regard to the fluctuations in the rate of consumption.

. It will be understood that the pump is constantly delivering gas whether the ,valve 29 works or not, and hence that the maximum desired ressure is uniformly maintained, said va ve simply compensating for variations in consumption. This uniformity of pressure is a matter of considerable importance, particularly in gas-furnaces, where it is not permissible for the intensity of the flames to vary.

So long as the pump is doing the work for which it is intended-21 '62., so long as the conthe delivered gas is constantly divided into two streams of varying proportions, one stream flowing through 22, the other returning through-by-pass 28 to the admission side of the pump, the volume passing through the by-pass decreasing as that passing through 22 increases, and vice versa, whereby either increase or reduction in the consumption of gas at the burners fails to cause a perceptible fluctuation in the pressure. at the burners. These fluctuations are caused, it should be remembered, without interruption (stoppage) in the floW.0f the gas through the by- 'sumption of gas does not overtax the pump pass so long as the pump is running, and the diaphragm is effective constantly throughout the entire flow of gas from the pump into pipe 20. It Will be understood that there must always be a reserve which can be drawn u on at any time for supplying increased emand at the burners which may occur. This reserve may be regarded as existing in the stream of surplusgas always flowing through the bypass. At any time this by-pass stream can be drawn upon or reduced to aflord a larger supply to the burners, and hence the pressure at the burners is uniform during all fluctuations in the rate of consumption. Infinitesimal variations in 45v screen 49. Both the gas-mam and the airr a mixture of air and gas, (or a mixture of the gas-pressure are sufficient to operate the variation in pressure at 22.

While my improvements are specially adapted to gas, still some features thereof are well adapted to air-pumps, blowers, or compressors, particularly the means for regulating the pressure at which air is delivered and maintaining the pressure uniform at the point desired. The excess air flows back to the admission side of the pump, thus avoiding the disagreeable noise heard when excess of air is allowed to escape into the room in which the pump is set up and also to some extent avoiding waste of power used in driving the pump.

It is not essential in all cases that means be employed for regulating the pressure at which the gas or air is delivered by the pump.

The hereinbefore-described apparatus may also be employed for the purpose of pumping gases,) particularly for use in gas-furnaces and elsewhere in cases where the quality of gas is high and it is desired to use mixed air and gas under pressure greater than the gasmain pressure.

Vhile in some cases a plain air-inlet valve may be provided upon the admission side of the pump or' inserted in the gas-main, so that the pump may draw in-gas mixed with air, manual regulation of the valve being depended upon for the purpose of securing the proper mixture, still I prefer to provide automatic means for determining the relative proportions of gas and air admitted to the ump. One form of such automatic means is illustrated at Figs. 3, 4, and 5, inserted between sections .1 1 of the gas-main. Air for mixing with the gas is drawn in through an inlet 48, which may be protected by a inlet open into-a vertical tube 50, the opposite walls of which are'perforated to form gas-outlet ports 51 and air-outlet ports 52.,

the former being shown above the latter.

The portion of the tube which is provided with said ports is confined within a chamber or box 52*, in which the gas and air entering the box through ports 51 and 52 may mix and flow through the section 1 of the gasmain and pipe 2 to the pump 4.

The flow of gas through'ports 51 is regulated 'by'a'valve 53, and the flow of airv through ports 52 is regulated'by a valve 54.

Said valves are formef cylindrically to fit in the tube-or valvechest 50 and are movable vertically therein for the purpose of opening and closin the orts. A single stem 55 is provided, eing connected to both valves,

for moving them simultaneously and posi tively up or down, said stem being preferably integral with valve 54. When the stem moves up, more air and more gas are admitted to the pump. When it moves down,

less air and less gas are admitted. Thus no matter whether the pump is delivering av large quantity or a small quantity of gas and air throughthe service-pipe 22 the proportion of gas and air in the mixture is uniform as long as the pump is in operation, which is a matter of much importance where gas and air are employed in gas-furnaces and elsewhere. It will be understood that the gas and air are delivered at uniform pressure regardless of the quantity being consumed, while the proportions of gas and air in the mixture do not vary, so that if the burners in a gas-furnace, for instance, are being supplied the heat can be depended upon to remain practically uniform as long as the furnace is in operation, which is a matter of prime importance in that art.

It would be within the scope of the invention seen at Figs. 3, 4 and 5 to regulate the movement or position of the valves 53 and 54 manually; but I prefer to provide automatic means for the purpose. To this end I provide a flexible or elastic (usually rubber) diaphragm 56 within a head 57, provided upon the bottom of the tubular valve-chest 50 and positively connected to valve-stem 55. It will be seen that the diaphragm is clamped between a large upper plate 58 and a small lower plate or washer 59, the stem 55 being formed with a guiding-head 60, that fits in the tube 50,and washer or clamp 59 being secured upon a nipple 61, depending from said head and penetrating the plate 58 and the dia hragm, said plate and diaphragm being held rigidly against said head. Thus when the diaphragm is either lifted or depressed the valves 53 and 54 move therewith and open or close the ports 51 and 52 accordingly. The movements of the diaphragm and valves controlled thereby are made to depend upon the volume of mixed gas and air being delivered by the pump-that is,'the quantity of the mixture flowing from the mixer to the pump depends upon the volume delivered to the service-pipe and consumed, the rotation of the pump being ,of course at uniform speed throughout all variations in the volume of mixture taken in thereby and forced through the service-pipe] To this end a pipe 62 furnishes an open communication from the suction pipe or inlet 2 of the pump to the upper side of the diaphragm 56- that is, to the upper chamber 63, formed by saiddiaphragm in the head 57. Assuming the diaphragm to be .at its lowest positior and both ports 51 and 52 closed, if the pum; is started into action apartial vacuum i: produced by its action 'in the inlet-pipe 2 and by reason of the c0mmunication62 t( the upper chamber 63 in head 57 a partia vacuum is produced in the latter, while below said diaphragm there is normal atmospheric pressure, the lower chamber being in open communication with the outside atmosphere through an opening 64. Said diaphragm is consec uently raised by atmospheric pressure, t uis opening said ports 51 and 52 and permitting the pump to draw air and gas therethrough.

If during the operation of the pum a large proportion of the burners 25 shoul be turned off, thus reducing the volume of mixture being consumed, the pressure in the service-pipe and in the vertical valve-pipe or structure 20 would increase, causing the valve 29 to open, so that the pressure in pipe 28 and inlet 2 would be brought to normal or at least increased. In consequence the vacuum in chamber 63'would be diminished and the diaphragm and valves would fall by gravity, thuscutting oil the supply of gas and air to an extent corresponding to the reduction in its consumption at the burners. other hand, if the consumption at the burners should be increased at any time the pressure in pipe 20 would become diminished, the valve 29 would close, a greater vacuum would be produced in pipe .2 and chamber 63, the diaphragm 56, with the valves, would be raised by atmospheric pressure, and the supply of gas and air to the pump be increased to an extent corresponding to the increased consumption at the burners. Of course during the operation of the pump the volume of gas being consumed is subject to both great and small fluctuations, and by the described means the admission of gas and air is under constant automatic regulation, so that the flame at each burner is kept uniform, regardless of the use of many or few other burners at the same time. It will be understood that it is of great importance to supply proper portions of gas and air to the pump and that by the described means the proper mixture is assured during all fluctuations in the rate at which the gas andair are drawn in by the pump, the principal function of the diaphragm 56 and its connections being not merely to permit the pump to draw in more or less of the mixed air and gas, as required, but to insure that whether the quantity drawn in be great or small at any time and whether the consumption of the mixture be uniform or variable the proportion ofair to gas shall always be uniform.

Since the gas itself varies in quality, I prefer to make provision for proportioning the gas-supply to the air-supply, poor gas permltting the addition of but little air, while rich gas may have a relatively larger quantity of air mixed with it. The valve 53 is accordingly made pendently of its automatic adjustment, already adverted to. It is mounted 'revolubly upon the stem 55, but confined thereto, so as to move vertically therewith, by means of On the manually adjustable, inde.

I a cross-pin or cotter 65 and washer 66, the valve resting upon a shoulder 67, formed near the top of the stem. This valve 53 is in the form of a cylinder, which at its lower end is cut away by first chambering and then slotting the same, so as to leave two shell-like sides 68, (seen best at Fig. 4,) at which figure said sides occupy ositions between the gasports 51 in the va ve-chest 50. By turning said valve 53, however, said sides may be turned aroundso as to cover said ports, and hence prevent or diminish the flow of gas therethrough, thereby to regulate the mixture ofgas and air in proportion to the richness of the gas or to secure a mixture of any desired quality, this regulation being manual and inde endent of the automatic movement of the va ve up and down, already described. The valve 53 may be rotatively adjusted by means of a head or finger piece 69, surmounting the valve-chest 50 and pinned to a short vertical stem 70, the latter being formed at its lower end with a head 71 wi thin the valvechest 'and provided with a pair of pendent vertical pins 72, Figs. 3 and 4, fitting into holes in valve 53, the pins enabling the head 71 to turn the valve around and being of sufficient length to accommodate the vertical movements of the latter, head 71 being immovable vertically. It will be understood that the attendant may adjust the fingerpiece 69 until by experimenting with the burners he perceives that he has a mixture of the richness desired, and then he may secuie the head-piece by a jam-nut 73, threaded upon the top of stem 7 0, so that so long as the pump is in use and during all fluctuations in the quantity of the mixture used its .richness shall have this predetermined quality: The top of the valve-chest is shown closed by a cap 74, which is threaded into the chestand centrally perforated to receive the stem 7 0.

Usually where a mixture of gas and air is burned individual air-inlets are provided at the burners, as in the Bunsen system, or else air is supplied under pressure and caused to draw in a supply of gas. In either case the burner is somewhat complicated, because of the provision for mixing the gas and air, and where the air is supplied under pressure it is necessary to have both air-pipes and gaspipes to the burners, making a double system of piping. By the apparatus seen at Fig. 3, however, all complication is avoided, as a single ,pipe-line conveys the mixed air and gas 1n proper proportions from the pump to the burner.

In many cases where it is desired to use Bunsen burners, but where the pressure of gas in the main is so weak that it is incapable of drawing in a sufficient volume of air (at the burner) to make a proper mixture it will be seen that the Fig. 3 apparatus can be used for the purpose of mixing at least a small portion of air with the gas, leaving it in such IIO itis usually found (lllllGulL may therefore not dependent upon the ,to maintain approximately conditionthat more air can be drawn in an the burner itself, if desired. Tlie'apparaius only increase the pressure of'gas delivered to a set of Bunsen burners, but may also mix a small quantity of air with the gas to advantage.

If the gas is either overcharged or. iindercharged with air, poor combustion results; but by this apparatus exactly the right proportion can be secured and inainiained. For use with Bunsen burners the apparatus may be regulated to mix in some air, which is a benefit, but not so much as to create danger of an explosion occurring in ihe. servicepipes, the remaining air that is necessarybeing taken in by the burners. The apparatus isof advantage for \Yelsbach lamps, in which to get theproper mixture of air, owing generally to the low pressure of gas at the burner, since not only may the pressure be increased, but air may be positively mixed with the gas in the service-pipes whether or not the mixture is supplied at high pressure to the burners.

Many variations may be resorted to in the mixture-governor, (seen at Fig-p3,) as well as in the remaining portions of the pumping apparatus-as, for instance, the lower chamber in the head 57 may be closed to the atmosphere and put into communication with the as-main at 1*.

Ifaving thus described my invention, 1 claim 7 1. An air or gas pump provided with a bypass between its admission and delivery sides, and having means unintermittently pressure of gas during the delivery thereof by the pump, for maintaining substantially uniform the pressure of the gas at the point or points of consumption during substantial fluctuations in the rate of consumption; said means including a valve,

in said by-pass, and a valve-controller always operable by the minimum useful pressure of the delivered gas, to'cause said valve to be constantly open during the consumption of the gas, to permit unintermitting return through said by-pass of gas in varying proportions during the flow thereof out of the pump. r

2. An air or gas pump provided with a bypass between its admission and delivery sides, a valve to control the, flow of gas through said by-pass, and avalve-actuator of far greater area than said valve and constantly subjected to the pressure of gas while it is flowing out of the pump, and movable by the minimum useful pressure of the delivered gas, to permit varying proportions of the gas flowing out of the pump to return in an unintermitting flow through said by-pass, uniform the pressure of the delivered gas-stream that does not return through said by-pass.

3. An air or gas pump provided upon its delivery side with a valve-seat, a rod having at one end a valve to it said seat, a casing in which said rod lits, a head upon said. casing, a diaphragm in said head and connected to said rod and of far greater area than said valve, and a by-pass between the delivery and admission sides of the/pump and controlled by said valve; said diaphragm being constantly exposed to the pressure of gas delivered from the pump, and of such area that the minimum useful pressure of the gas thereon keeps said valve constantly open.

- i. An air or gas pump provided with a bypass between its admission'anddeliverysides,

and having means unintermittingly dependout upon the pressure of gas during the delivery thereof by the pump, substantially uniform the pressure of the gas at the point or points of consumption during substantial fluctuations in the rate of clinsumption; said means including a valve in said hy-pass, a valve-controller always operable by the minimum useful pressure of the delivered gas, to cause said valve to be constantly open during the consumption of the gas, to permit uninternntting return through said by-pass of. gas in varying proportions during the flow thereof out of the pump, and means for regulating the resistance of said pressure-maintaining means to the pressure of the outflowing gas, thereby to regulate the minimum pressure of the gas to suit varying requirements 5. An air or gas pump provided with a bypass between its admission and delivery sides, a valve to control the llow of gas for maintaining through said by-pass, a valve-actuator of far greater area than said valve and constantly subjected to the pressure of gas and mov-,

while it is flowing out of the pump, able by the minimum useful pressure of the delivered gas, to permit varying proportions of the gas flowing out of the pump to return in an unintermitting flow through said bypass, to maintain approximately uniform the pressure of the delivered gas-stream thatv does not return through said by-pass, and means for changing at will the resistance of said actuator to said gas-pressure, thereby to regulate the minimum pressure of the gas to suit varying requirements.

6. An air or gas pump provided upon its delivery side with a valve-seat, a rod having at one end a valve to fit said seat, a casing in which said rod fits, a head upon said casing,

va diaphragm in said head and connected to said rod andof far greater area than said valve, a by-pass between the delivery and admission sides of the pump and controlled by said valve; said diaphragm being constantly exposed to the pressure of gas delivered from the pump, and of such area that the minimum useful pressure of the gas thereon keeps said valve constantly open, a

weight-holder connected to said diaphragm,

1 and a set of movable weights for resting u on said holder to vary the resistance of said iahragm to the gas-pressure, thereby to reguate the minimum pressure of the gas to suit 5 varying requirements.

7. The combination with an air or gas pump having a by-pass from its delivery side to its admission side,.of a valve associated with said by-pass, ahead, a diaphragm in said head and having far more extensive area than said valve, a rod passing throughsaid head and connected to the diaphragm; a set of weights to act upon said rod to vary at will the resistance of said diaphragm to the gas-pressure; said valve being connected to said rod, and said diaphragm being constantly subg'ect to the pressure of gas as it flows out o the delivery side of the pump, and of sufficient area to enable the minimum useful as-pressure to hold said valve open.

8. T e combination with an air or gas pump having a byass from its delivery side to its admission si e, of a valve for said bypass, a head, a diaphragm in said head and connected to said valve, a delivery or service pipe leading from the delivery side of the pump to a device which consumes the gas, and a connection leading from the consumptionend of said delivery-pi e back to said head; saiddiaphragm being 0 such area that it is caused by the minimum useful gas-pressure to hold said valve constantly open during the flow of gas through said deliverypipe.

9. An air or gas pump provided upon its delivery side with a valve-seat, a rod having at one end a valve to fit said seat, a casing in which said rod fits, a head upon said casing,

and a diaphra m of relatively great area mounted in sai head and connected to said rod, the rod being rovided with a passage for the fluid to said lead, and the pump being also provided with means for conducting the escaping fiuid from said valve to the admission side of the pump.

10. The combination with an air or to its admission side, of a valve in said pas sage, a service-pipe leading from said delivery side and having a remote discharge portion, and means for enabling said valve to be controlled by the pressure of the fluid either immediately at the delivery side of the pump or at said remote discharge portion of, the service- 'ipe at will.

11. e combination with an air or gas pump having a passage from its delivery side to its admission side, of a valve in said passage, a head, a diaphragm in said head and connected to said valve, a service-pipe leading from said delivery side and having a remote dischar ing portion, a valved connec tion leading cm the discharging portion of said service-pipe to said head, and a valved passage directly from the delivery side of the pump to said head. I

GEORGE MACHLET, J-R.

Witnesses:

PHILIP C. OSTERMAN, GEORGE L. HIRTZEL, Jr.

as 'pump having a passage from its delivery side 

